Technologies for manufacturing electronic circuit components and representative LSI products thereof have become widespread, and manufacturing is shifting to low-cost regions in Southeast Asia and the like. Up to the 1990s where manufacturing was conducted by only a few specialized makers with advanced technology, the products were mainly distributed through legitimate channels. For this reason, problems caused by the commercial distribution of counterfeit products and shoddy items did not surface.
If logical design data of an LSI product is available, a circuit of the same logical operation can be made even according to a different manufacturing process (factory). Instances where counterfeit products are made by reverse-engineering an electronic circuit component, for example, an LSI product of an advanced technology have also exponentially grown in number. Second-hand items and defective items that should have been discarded in the manufacturing process are sometimes included, in addition to the distribution of counterfeit products. In particular, since an expensive LSI product worth several hundreds of dollar per chip is not a rarity, counterfeiting is a great benefit and would be likely to further increase. The need for countermeasures is imperative.
It is easy to determine the authenticity of a counterfeit product that only copies the outer appearance but cannot operate at all. However, a counterfeit product that has poor quality but performs the same logical operation as that of a genuine is difficult to discriminate.
The counterfeit electronic circuit components certainly incur financial damage and pose a threat to the safety of users using products as well, leading to a problem of credibility of the product maker. Hence, it is especially important to discriminate a counterfeit product that looks like an authentic item capable of operating correctly.
Whether an item is an authentic item made at an authorized factory can be determined by opening the package and checking the manufacturing process, as a matter of course. However, the cost of such a destructive inspection is high, and the destroyed authentic item is unusable. There is also a trick to selling counterfeit products that are mixed among authentic items, and a sampling inspection alone may fail in finding the counterfeit products. Hence, it is very important to develop a technique for nondestructively determining the authenticity of an LSI product.
To prevent the infiltration of imitations in the trade stream, the industrial organization SEMI (Semiconductor Equipment and Materials International) is pushing forward an ISO of “T20” specifications of traceability technologies (NPL 1).
In “T20”, a third-party certification authority issues unique IDs (identification data). Semiconductor makers add the IDs to products and submit the databases of products managed by the IDs to the third-party certification authority. The user of an LSI product can confirm the authenticity by inquiring of the third-party certification authority about the ID added to the product.
However, adding and managing IDs cost several cents/piece when issuing an enormous number of IDs. This is not problematic for, for example, expensive processors that are worth several hundreds of dollar, but greatly increases the cost of LSI products priced at only several dollars. As for the ID form, a two-dimensional barcode is expected to be used on the package of an LSI product, and a hologram or an RFID (wireless ID tag) for a packaging box. However, it cannot prevent counterfeit of the barcode, hologram, or RFID.
There have also been developed a technique for directly marking an ID in an LSI chip by laser (PTLs 1 and 2), but not in the package or packaging box of an LSI product. This technique is suitable for managing silicon wafers or bare chips. However, once an LSI chip is packaged, its authenticity can be confirmed only by destructive inspection. A technique of printing dots on an LSI product by Ag nanoink and nondestructively reading the dots by X-ray fluoroscopy raises fears of an adverse effect of the ink on the LSI device (PTL 3). The laser marking or nanoink printing is also disadvantageous in needing an apparatus to perform special marking.
Studies on PUF (Physical Unclonable Function) are also making progress, which is a technique of converting a physical variation of LSI devices into digital data and using it as an ID, instead of writing an ID later (NPLs 2 and 3 and PTL 4).
Some PUF products use the fact that data in an SRAM takes a random value unique to the chip immediately after being powered on, and some products using the value as an ID are coming along.